Mechanical lead pencil



Sept. l2, 1939. l. cHEsLER MECHANICAL LEAD PENCIL Filed Aug. 15, 1955 w N $1 m mi Mv ma QN m QN S1 NLIYUH hm. Wm. .IHITH Patented Sept. 12, 1939 UNITED STATES MECHANICAL LEAD PENCIL Isidor Chesler, West Orange, N. J., assignor to Eagle Pencil Company, a corporation of Dela- Waffe Application August 13, 1935, Serial No. 35,921k

12 Claims.

My present invention relates to mechanical lead pencils, more particularly of the screw propeller type.

It is among the objects of the invention to pro- I vide a pencil of the above type in which protrusion of the eraser as its exposed end is consumed is effected by the same mechanical movement Vas is the propulsion of the lead, and this without the need for threading the eraser into its ferrule and with the use of pencil erasers now on the market.

A feature of the invention is the keying interlock of the slotted lead tube with respect to the eraser ferrule, by which said tube is turned, the latter being irremovably locked to, but freely rotatable upon the pencil case. This result, in a preferred embodiment, is accomplished by spreading and reversely bending the split longitudinal extension of said tube to overlie the eX- terior of the rear end of the case and lodging said overlying lengths in corresponding longitudinal grooves in the ferrule.

Another feature is the blocking washer at the split extremity of the lead tube for preventing the propeller from being retracted out of its helical track and yet permitting the rear extremity of said propeller to protrude from beyond the real` end of the lead tube, against the sheet metal holder for the eraser, in advancing the latter to 30 protrude from the ferrule as it is consumed.

Another feature is the multiple beads on the ferrule into which the eraser cup is successively latched in the successive settings of the eraser by the retracting movement of the propeller.

35 In the accompanying drawing, in which is shown one of various possible embodiments of the several features of the invention,

Fig. l is a view of the pencil in longitudinal cross-section,

Fig. 2 is a similar fragmentary view on an enlarged scale, of the front end of the pencil,

Fig. 3 is a view similar to Fig. 2 of the end of the pencil,

Fig. 4 is a view in transverse r line 4-il of Fig. 3,

Fig. 5 is a view similar to Fig. 4 on line of Fig. 3,

Fig. 6 isv a side elevation with parts broken away, of the lead tube, and,

Fig. 7 is a fragmentary perspective view of the ferrule.

Referring now to the drawing, there is shown a pencil, which in its general outlines is similar to that of my prior Patent No. 1,956,271 dated April 24 1934, and as to said general structure will,

cross-section, on

(Cl. 1Z0-38) therefore, be described herein only in sufiicient detail to aid in understanding the improvement to which the present invention is directed. The case I@ is shown of molded plastic material, preferably of the phenol formaldehyde condensation u.5 group, and has molded therein a helical track l i extending the entire length of the casing up to the tapered tip I2. Within the case extends the lead tube I3 slotted at I4 and preferably bearing on the inner wall of the helical track II andlO adapted to be rotated therein by turning of the eraser ferrule I5. The tube is longitudinally slotted at I6 near its rear end diametrically opposite slot I4 and the straps thus formed are bowed outward at I1 for clutch engagement with 15 respect to the helical track to afford a secure friction hold, as described and claimed in the `copending application of Joseph Meilner, Serial No. 13,378, filed March 28, 1935.

Mounted in the lead tube is a propeller com- 20 prising a length of metal wire i8 with a lug illustratively formed as a loop i 9 extending through the slot I4 and riding in the helical track I I. The propeller includes a tubular section 20 into which the wire i 8 extends, which tubular section has .2.5 a propeller roller 2I protruding therefrom and also riding in the track II, preferably a pair of turns in advance of the lug I9. At the forward end, the tube has a clutch 22 for grasping the rear end of the lead 23 which protrudes through the ,30 metal tip I2 of the pencil. By this arrangement, it is seen that the lead will be propelled and repelled, depending on the direction of rotation of the ferrule I5 with respect to the case Il). In the forward movement of the propeller, the roller S 2| after it reaches the extremity of the track, is arrested, and the continued advance of the propeller lug I9 in the continued rotation of the propeller will cause the rod I8 to advance in the tube 20 and expel the unused short stub of lead.

According to the present invention, the interlock by which the ferrule drives the lead tube i3 is considerably improved with respect to the showing of the prior patent. As shown, the lead tube is of greater length than can be accommodated in the case, but its rear extremity is longi` tudinally slit, and the strips thus formed are bent outward at 24 and reversely bent at 25, to form U-shaped conformations integral with the tube I3. These U-shaped extremities overlap the exterior of the case end, which is reduced in diam.- eter at 26, so that said strips 25 extend substantially flush with the outer wall of the case. Preferably, the case has a peripheral groove 27 in 55 which ride corresponding indentations 28 on the strips 25 of the lead tube.

The shank of the ferrule is preferably formed with wide, shallow longitudinal grooves 29 therein preferably four of such grooves being formed for ornamental appearance, as appears best in Figs. 4, and 6. The ferrule being telescoped over the case, the reversely extending strips 25 of the lead tube are accommodated by two diametrically opposite grooves 29 for a keying connection with respect to the ferrule. The ferrule is preferably indented at 3l! to form a bead at the region of the peripheral groove 21 to prevent removal from the case, but to permit free rotation thereon in either direction.

It is apparent that the lead tube is securely keyed with respect to the ferrule and turns as a unit therewith. So secure is this mechanical connection that there is no possibility under even extreme conditions of use, of lost motion or slippage and the connection is adequately strong to overcome the friction engendered, even where an oversize lead is used.

By the construction shown, the ferrule I5 alone is accurately positioned concentrically of the case and the lead tube I3 yieldingly accommodates itself with respect to the case, to ride therein by a floating action, regardless whether or not the parts have been made with great precision for concentricity. Thus, in rotating the ferrule, uniform resistance is encountered and uniform movement results, the 'jumpiness or alternation of high and low resistance commonly encountered in screw propelled pencils being obviated.

Whenever the eraser has been consumed to substantially the rim of the ferrule, then by reverse, return or retraction movement of the propeller, its rear extremity 318 is caused to emerge from the rear end of the tube I3 to engage the metal cup 34 of the eraser and push the same rearward to operative position. To guard against slippage of the eraser in use, the ferrule is preferably provided with a series of spaced beads 3l, 32 and 33 forming internal grooves in any of which the sheet metal cup for the eraser 3'! may latch, said cup having a base 34 and upstanding tongues 35 with out-turned grooves 35 forming beads to register with any of the grooves. The eraser and holding cup is preferably according to my prior Patent No. 1,859,433 of May 24, 1932.

To prevent the lug I9 of the propeller from being retracted out of the track, it is preferred to provide a stop washer 39 which embraces the lead tube and affords a tongue 4i) entering the slot I4 thereof. This stop washer blocks the retraction movement of the lug I9, without interfering with the propulsion of the extremity 38 of the propeller wire rearward of the lead tube, in effecting the eraser setting. In the extreme position to which the propeller may be retracted, the eraser is substantially completely expelled from the case and may be readily withdrawn.

While the invention is preferably embodied in the construction shown, with a case, having its helical track molded as a unitary piece therewith, it is understood that the invention is applicable also in constructions of sheet metal or other material with separate helical tracks.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a mechanical pencil, a case, a ferrule rotatable thereon, means locking said ferrule against removal from said casing, said ferrule having a plurality of peripheral internal grooves therein, an eraser having a holder cup with a bead structure to snap into any of said grooves, a helical track in said case, a propeller movable along said track, means connecting said ferrule to said propeller so that rotation of said ferrule will cause the propeller to move forward or backward along said case, the rear end of said propeller being adapted in the retracting movement to engage said eraser cup to advance the same along said ferrule, to snap out of one groove and be snapped into the neighboring groove until the eraser has been consumed, and finally by retraction of the propeller to its extreme position to be ejected from the ferrule.

2. In a mechanical pencil, a case, a ferrule rotatable thereon, means locking said ferrule against removal from said case, said ferrule having a plurality of peripheral internal grooves therein, an eraser having a holder cup with a bead to snap into any of said grooves, a helical track in said case, a propeller movable along said track, means connecting said ferrule with respect to said propeller to move the same forward or backward along said case, the rear end of said propeller being adapted in the retracting movement to engage said eraser cup to advance the same along said ferrule, to be snapped into the neighboring groove until the eraser has been consumed and nally by retraction of the propeller to 'its extreme position to be ejected from the ferrule, and means in the path of that portion of the propeller riding along the track to prevent the same from being retracted beyond the extremity of the track.

3. A mechanical lead pencil comprising a case, having a helical track unitary therewith, and. having a slightly reduced rear extremity, a ferrule telescoped over said extremity and having a bead, registering with a corresponding peripheral groove on said extremity to permit free rotation, but to block removal of said ferrule from the case, an eraser having a sheet metal holding cup lodged in said ferrule, a slotted tube open from end to end, keyed at one extremity to said ferrule to be rotated thereby, a propeller lodged in said tube and having a lug extending through the slot thereof into the helical track, the rear end of said propeller being adapted in the retracting movement thereof to engage the said eraser cup and to advance the same in its ferrule, and a rigid washer about the rear extremity of said tube, blocking the retraction of the propeller to prevent the same from being backed out of its track.

4. A device of the character described comprising a case having a helical track therein, a longitudinally slotted tube in said case, a propeller in said tube having a lug protruding through the slot of said tube into the helical track, an operating ferrule over the end of said case, said tube being slit and reversely bent to overlap the exterior of the case extremity, said ferrule having an internal groove longitudinally thereof for lodging said reversely bent portion of the tube to afford a keying connection with respect thereto vand means preventing removal of the ferrule from the case while permitting free rotation of the ferrule upon the case for movement of the propeller in said tube for displacement of a consumable element protruding from one end of the unit.

5. A device of the character described, comprising a case, a ferrule on one end of said case adapted to be rotated relative thereto, an eraser, a one piece sheet metal eraser holder embracing the periphery of said eraser and having an end wall extending across the bottom thereof, said holder being lodged in said ferrule and having an axially slidable engagement therewitlma longitudinal propeller member in said case, means including a helical movement, and responsive to the rotation of said ferrule in one direction for moving said propeller member away from said eraser holder, and means responsive to the mere rotation of the ferrule in the opposite direction for retracting said propeller member into pushing engagement with the end Wall of said eraser holder to slidably advance the latter out of said ferrule.

6. A device of the character described having a ferrule at one end thereof, said ferrule having a plurality of parallel internal peripheral grooves and adapted to be successively snapped into the other grooves, a propeller within said casing, having a continuous drive connection with respect to said ferrule, the rear end of said propeller being adapted to engage the cup mount of said eraser and to advance the latter in a step by step movement to snap successively from each groove to the next groove in the ferrule.

7. A device of the character described compeller in all of the latters movements, said slotted tube affording an opening for retraction of the back end of said propeller to move the eraser 8. A device of the character described comprising a case having a helical inner structure rigid therewith, a ferrule rotatably aixed to one end of the case, a propeller having a lug coacting with said helical structure, connecting means between said ferrule and said propeller for rotating said propeller in said case upon rotation of said ferrule, a longitudinally slotted tube in which said propeller is lodged, an eraser having a mounting cup therefor, frictionally xed in the ferrule and detached from said propeller in all of the latters movements, said slotted tube affording an opening for retraction of said propeller to move the eraser out of the ferrule by the pushing action of said propeller on said cup upon rotation of said ferrule in one direction, and means to limit the retracting movement of the propeller to keep its lug within the helical structure.

9. A device of the class described comprising a case, a helical track rigid with said case and extending substantially the entire length thereof, a ferrule aiixed to one end of said case, and having free rotary movement thereon, an eraser removably mounted in said ferrule, a slotted tube rigid with respect to said ferrule and slotted its full length, a. propeller in said tube having a lug protruding from the slot thereof into the helical track, connecting means between said ferrule and said propeller for rotating said propeller upon rotation of said ferrule, said tube having blocking means at the rear end thereof for limiting the retraction of the lug of the propeller to` limit the protrusion of the rear end of the propeller beyond the lug for corresponding advance of the eraser l with respect to the ferrule.

10. A mechanical pencil comprising a case, a ferrule rotatable on the end thereof and blocked against removal therefrom, an eraser having a sheet metal holding cup with a latch connection with said ferrule, said case having a helical guide, a propeller lodged in said case, and having a lug riding on said guide, means connecting said ferrule to said propeller to rotate the same in unison while permitting the propeller to perform an advancing or a retracting movement along said helical guide, the rearward extremity of said propeller being moved beyond the extremity of said guide to engage said eraser cup and advance the same With respect to the ferrule.

1l. A device of the character described comprising a molded case, having a slightly reduced cylindrical extremity with a narrow peripheral track, the rear tube being split, the split ends thereof reversely bent to overly the reduced extremity of the case and having a transverse indentation lodged in said peripheral groove, a ferrule telescoped over said reduced extremity, and having wide internal longitudinal grooves therein, accommodating said reversely bent ends or" the tube for keying connection thereunit including a sheet metal cup having a latch connection with said ferrule and adapted to be pushed out of the ferrule by the retracting movement of the propeller along said track.

12. A device of the character described comprising a case, a helical track therein, a ferrule supported on one end of said casing, a longitudinally slotted tube in said case, a propeller in said tube having a conformation extending through the slot of said tube and into said track, means operable from the outside of the case for effecting relative rotation of said propeller and 

